A majority of state (55%) and federal (63%) prisoners in the U.S. have at least one child under the age of 18 years. Parental criminality, arrests, and incarceration are at least modest predictors of violent and serious child delinquency, and there is evidence that the impact of parent criminality on child antisocial behavior is mediated by parenting practices. A variety of non-standardized programs aimed at improving inmate parenting practices have been delivered in U.S. prisons, but rigorous scientific knowledge on the impact of such programs on inmates and children is non-existent. To begin to remedy this lack of knowledge, we propose a randomized preventive intervention trial to test the impact of parent management training on the children of incarcerated parents. This trial will be conducted with the full cooperation and support of the Oregon Department of Corrections (DOC) and the Oregon Governor, and services for the intervention will be paid for by the DOC. Incarcerated parents (.N = 400; 50% female; 50% minority) will be randomized into a parent management training condition (PMT; g = 200) or a services-as-usual condition (SU; _n= 200). PMT will combine current standard of practice prison parent education curricula with state of the art, empirically-based parent management training content and methods. In addition, caregivers will receive weekly mailings as well as weekly phone calls as part of the PMT condition. Participants (i.e., inmates, caregivers, and a focus child in elementary school [grades 1 through 5]) will be assessed at baseline, during intervention, following intervention, after release from prison, and 6 months after release. School and court records and teacher data will be collected at baseline and 6 months after release. Collected data will allow for an examination of whether a theoretically and empirically based, group-delivered PMT program for incarcerated parents positively impacts the behavior, well-being, and relationships of the inmates, their children, and the caregivers of their children while the inmate is inside and outside of prison; and whether any changes in child and caregiver behavior, well-being, and relationships are mediated by treatment-initiated changes in inmate parenting practices.